How do Mendel’s experiments show that traits are inherited independently?
Mendel's experiments demonstrated that traits are inherited independently through his work with pea plants having two contrasting characteristics.
Mendel proposed that two copies of factors (now called genes) controlling traits are present in sexually reproducing organisms. These two copies may be identical or different, depending on the parentage. Both the father and mother contribute practically equal amounts of genetic material to the child, meaning each trait will have two versions in each child.
For this inheritance mechanism to work, each germ cell must have only one gene set. This is because each pea plant must have two sets of all genes, one inherited from each parent. The germ cells make a single set of genes from the normal two copies that all other cells in the body have.
If progeny plants inherited a single whole gene set from each parent, then the two characteristics 'R' and 'y' would be linked to each other and cannot be independently inherited. However, Mendel's experiments showed that traits are inherited independently, proving that germ cells carry single gene sets that combine during reproduction.
This independent inheritance occurs because different traits are controlled by different genes that segregate independently during gamete formation, allowing for various combinations of traits in the progeny.
Explanation
The textbook context explains Mendel's contribution by establishing that organisms have two copies of genes (factors), one from each parent. The key evidence for independent inheritance lies in the fact that if traits were linked (inherited together as a single unit), the experimental results would not work. The context specifically mentions that characteristics 'R' and 'y' would be linked and cannot be independently inherited if progeny received a whole gene set. Since Mendel's experiments did work, it proves that traits segregate independently during gamete formation. The requirement that each germ cell has only one gene set (not two) is crucial for independent inheritance to function.